GEOLOGIC TIME IN CONNECTICUT
Boundary
age (Ma)		 Eon Era  Period Epoch Events and Life
0.011 P
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c		 Quaternary Holocene Humans arrive, ecology changes
1.8 Pleistocene Dramatic climate oscillations, rise & fall of sea-level cutting scarps along major rivers; ice sheets cover & uncover Ct.; 
5.0 Tertiary  Pliocene Marine coastal sedimentation 
23 Miocene erosional interval
38 Oligocene erosional interval
54 Eocene Semi-tropical plants in Vermont
66 Paleocene erosional interval; mammals expand
(mass extinction)
146 M
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c		 Cretaceous Shallow sea covers coastal New England (sand now under L.I. Sound); inland regions erode with uplift; birds expand
201 Jurassic Atlantic Ocean opens, south-flowing rivers (Ct., Thames, etc.) develop; climate becomes wetter; dinosaurs expand 
(mass extinction)
250 Triassic Rifting of Pangaea begins: Deposition of land sediments in Hartford rift basin; SW-flowing rivers meander in semi-arid climate; primitive dinosaurs
(mass extinction)
286 P
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c		 Permian ALLEGHANIAN OROGENY: Alleghanian mountain building due to continental collision; Stony Creek granite and eastern pegmatites form; Pangaea completed
325 Pennsylvanian Coals deposited in coastal swamps in SE New England, Alleghanian orogeny begins
360 Mississippian Passive margin sedimentation; early amphibians crawl ashore
410 Devonian ACADIAN OROGENY: Sediments from Acadian mountains deposited in eastern Ct; granites & western pegmatites melted by deep burial, rocks metamorphosed
440 Silurian Taconic highlands eroded; submarine basin in central New England continues to be buried; early land plants
505 Ordovician TACONIC OROGENY: rocks in western Ct. moved; marine muds and sands in central Ct. buried and metamorphosed
544 Cambrian Carbonate deposition on passive margin; marbles in NW Ct.; earliest shelled fossils ("Cambrian explosion")
650 P
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c		 Neoproterozoic 600-550: Late phase of Iapetan rifting (some basalts extruded)
   
900 750-700: Early phase of Iapetan rifting 
  Mesoproterozoic  1100-950: GRENVILLIAN OROGENY
   oldest basement rocks in NW Ct.
1600  
  Paleoproterozoic 

 

  oxygen increases
   
2500  
 
 
 
 

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3800 Atmosphere develops
 
 
 

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  Earliest signs of life (bacteria) 
   
   
4600 Formation of the Earth and cooling of the crust